In some applications, it may be necessary to regulate the pressure within remotely located zones. For example, some machines and equipment may include chambers that are pressurized or evacuated during operation of the equipment. Examples of such machines may include, but are not limited to, chemical mechanical polishing (CMP) machines.
A pressure sensor inside a measurement chamber may only measure pressure within that measurement chamber, not within a zone that is coupled to the chamber but remotely located with respect to the sensor. As a result, a pressure control system that only uses pressure measurements by a pressure sensor located inside the measurement chamber may have to assume that the pressure in the remote zone is equal to the pressure in the measurement chamber. Often, however, the pressure in the remote zone may not be equal to the measurement chamber pressure. For example, when localized pressure transients occur in the measurement chamber, the pressure in the remote zone may be not affected in the same way so that the pressure in the two locations are not equal. This may result in a substantial degradation of the performance of the pressure control system.
Accordingly, there is a need for systems and methods that allow the pressure within remotely located zones where pressure is not measured directly to be controlled accurately.